This invention relates to a cyclone separator and, more particularly, to such a separator for separating solid fuel particles from gases discharged from a combustion system or the like.
Conventional cyclone separators are normally provided with a hopper connected to their lower end to collect the solid particles from the separator. The separator and the hopper are usually provided with a monolithic external refractory wall which is abrasion resistant and insulative so that the outer casing runs relatively cool. Typically, these walls are formed by an outer metal casing and two inner insulative refractory materials to protect the outer casing from high temperatures and reduce heat losses. However, in order to achieve proper insulation, these layers must be relatively thick which adds to the bulk, weight, and cost of the separator and hopper and require controlled, relatively long, start-up and shut down times prevent cracking of the refractory. Also, the outside metal casing of these designs cannot be further insulated from the outside since to do so could raise its temperature as high as 1500.degree. F. which is far in excess of the maximum temperature it can tolerate.
Further, most conventional cyclone separators require relatively expensive, high temperature, refractory-lined ductwork and expansion joints between the reactor and the cyclone, and between the cyclone and the heat recovery section, which are fairly sophisticated and expensive. Still further, conventional separators formed in the above manner require a relatively long time to heat up before going online to eliminate premature cracking of the refractory walls, which is inconvenient and adds to the cost of the process. Also, other cyclone separators may require a separate roof tube circuit which still further adds to the cost of the system.